Here's my server setup (Password is Pass99.):
Here's what happens when I try to connect using FileZilla:
Here's what happens when I try to connect using the Windows FTP client:
When I first used FTP, it worked. Then I didn't use it for about 3 weeks. After that, I got this problem. During that time, I changed nothing except my project file (ladder and HMI changes). I tried an older project file from before the problem occurred and still get the problem. I also tried connecting from a different PC - still no luck. Someone suggested running the client as administrator. I'm running an admin account on both PC's.